Add takeover delay to quantum-ha-tool

Add a takeover delay to the quantum-ha-tool to ensure we do
not try to aggressively takeover.  We want to ensure an agent
is offline for some period of time (TAKEOVER_DELAY seconds)
before we begin a migration.  We also randomize it a bit in the
event that this script is being run in parallel from several hosts.

Change-Id: Ied9a75791b27af310f81f4cec327b3699fbae7ed
Parameterize agent report timers

* Ensure that report_interval and agent_down_time
are both parameters that can be overriden
* Relax the default agent_down_time to 15 seconds
since 4 seconds (1 second > report_interval) proves
unreliable with a large number of routers

Change-Id: Id9bfcd01ba36553b4fb1371238d58de77435a9aa
Add ovs-dpctl-top tool for better troubleshooting

Nicira added a tool to emulate top for ovs-dpctl output
in this commit:

http://git.openvswitch.org/cgi-bin/gitweb.cgi?p=openvswitch;a=commit;h=14b4c575c28421d1181b509dbeae6e4849c7da69

This tool allows you to quickly, and in real time, get better insight
into what the traffic looks like on any given OVS node.

This is especially useful on L3 agent (logical router) nodes as it
will allow you to pinpoint trouble flows/links/ips which may be
causing bottlenecks or consuming an inordinate amount of CPU.

Change-Id: I54c9e6e86ce0942c206227b45123d17ca27109be
Merge "Add ovs-dpctl-top tool for better troubleshooting"